Coatings which protect roofing substrates that are based on specifically designed elastomeric polymers are referred to as roof mastics. These coatings to be effective should be able to pass the tests for (1) water ponding (2) water vapor transmission (3) cold temperature flex (4) flame retardancy and (5) reflectance.
Coatings which are corrosion resistant and can adhere to a large variety of substrates including rubber, foam, metal and the like are useful for many applications depending on the type of binder or fillers that are used.
Having a basic coating composition with good mechanical and chemical properties will reduce the cost of manufacture and market price of the products. The compositions would be environmentally advantages if there can be used recycled waste material. Disposal of used tires has become an environmental problem. The reclamation of tires for other uses would be helpful in solving some of the environmental problems.
U.S. Pat. No. 5,362,759 to Hunt et al, which is herein incorporated by reference, discloses rubber crumb obtained by heat treating used rubber under reduced pressure with microwave energy. The rubber crumb of this patent is particularly useful in the present invention. According to the method taught in Hunt et al., the curd rubber is stirred while being simultaneously subjected to microwave energy, as a result, uniform heating is carried out throughout the charge to desulfurize the rubber and to vaporize any process oil entrapped in the rubber. The vulcanized rubber is heated by microwave to a temperature of about 50.degree. to 100.degree. C., preferably about 78.degree. C. The heating time is generally about 15 minutes. The temperature is controlled by a temperature sensor and automatically controls the operation of the microwave vacuum reactor cell. The vapors emanating from the process oil entrapped in the rubber and the gases generated by the desulfurization reaction are vented through the vapor outlet means.